The present invention relates to an N-formal-containing preservative with reduced formaldehyde and amine emission, and to the use thereof.
Formaldehyde donor compounds, for example O-formals and N-formals, are used as biocides in a series of products and preparations for reducing microbial growth. A series of documents is known which describe the use of O-formals and N-formals.
DE 42 42 082 A1 discloses hydrolysable polymeric resins and binders for antifouling paints. As well as hydrolysable polymeric resin, the binder system can also comprise cobiocides, such as dichlorophenyl-dimethylurea or 2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine.
U.S. Pat. No. 4,655,815 A1 discloses a synergistic antimicrobial mixture of 2-bromo-2-bromomethylglutaronitrile and formaldehyde donor. Examples of formaldehyde donors are 2-[(hydroxymethyl)amino]-2-methylpropanol, 2-hydroxyethyl-2-nitro-1,3-propanediol, mixtures of 5-hydroxymethyl-1-aza-3,7-dioxabicyclo-(3.3.0)octane, 2-[(hydroxymethyl)amino]ethanol, 1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride, N-(3-chloroallyl)heximinium chloride, hexamethylenetetramine(hexamine) halohydrocarbon quats and dimethyloldimethylhydantoin.
EP 0 327 220 B1 describes a synergistic combination of selected formaldehyde donor with iodopropargyl compound. The disclosed compositions comprise, as preferred iodopropargyl compound, iodopropynyl butylcarbamate (IPBC) and, as formaldehyde donors, nontoxic and odour-free compounds which are suitable for use in bodycare compositions. However, the formaldehyde donors disclosed are relatively expensive substances.
DE 41 41 953 A1 discloses microbicidal compositions which comprise, as active ingredients, a combination of at least one iodopropargyl derivative and benzyl alcohol mono(poly)hemiformal. Moreover, further compounds, e.g. formaldehyde or its donor substances or guanidine derivatives, can be added to the active ingredient combination.
U.S. Pat. No. 5,428,050 A1 and U.S. Pat. No. 5,496,842 A1 disclose a water-soluble preservative mixture which comprises powders of (a) one or more methylol compounds or equivalents thereof, and (b) iodopropynyl alcohol, its ester, carbamate or ether derivative. The patent specifications disclose the synergistic combination of (a) and (b). However, undesired formaldehyde emissions are not discussed.
DE 197 22 858 A1 relates to compositions based on iodopropynyl and formaldehyde donor compounds and use thereof as preservatives. Examples of formaldehyde donor compounds are N,N′-methylenebis(5-methyloxazolidine), 3,3′-methylenebis(tetrahydro-2H-1,3-oxazine) and 1-aza-5-ethyl-3,7-dioxabicyclo[3.3.0]-octane. The compositions comprise iodopropynyl butylcarbamate as preferred iodopropynyl compound. As the IPBC content increases, the formaldehyde emissions increase, thus the biocidal effectiveness of the compositions in the gas phase also increases with increasing IPBC content. In the compositions, an addition of certain glycols has a positive influence on the odour of the compositions and reduces the emission of relatively volatile substances such as, for example, formaldehyde. The use of compositions which comprise iodopropynyl compounds is thus precluded if particularly low formaldehyde emissions are desired, or in the case of use in environments which are incompatible with iodopropynyl compounds. Moreover, compositions comprising iodopropynyl compounds have a tendency toward undesired discolorations.
The preservative of DE 40 26 756 A1 comprises a mixture of (a) an organic acid, (b) a monophenyl glycol ether and (c) a guanidine derivative. Further optional biocides mentioned are imidazolidineurea and/or hydantoin derivatives.
DE 199 61 621 A1 relates to compositions which comprise at least one bactericidal N-formal, at least one fungicide and at least one stabilizer. Particularly preferred formals are triazinetriethanol and N,N′-methylenebis(5-methyloxazolidine).
DE 198 42 116 A1 discloses stable microbicidal compositions which comprise derivatives of methylenebisoxazolidine and 1H-benzimidazol-2-ylcarbamic acid. Moreover, further active ingredients may be present, for example dimethylolurea, bis(hydroxymethyl)-5,5-dimethylhydantoin, diazolidinylurea, sodium hydroxylmethylglycinate or diuron (1,1-dimethyl-3-(3,4-dichlorophenyl)urea. However, these substances are relatively expensive and/or toxic. Carbendazime (methyl 1H-benzimidazol-2-ylcarbamate) is regarded as undesired due to its toxic properties (cancerogenic, mutagenic, reproduction-toxic) and its classification as a toxic substance (from 0.1% use concentration), although it is difficult to replace due to its good microbicidal effect.
DE 101 22 380 A1 discloses an alcohol-free liquid concentrate based on carboxylic acid salts and stabilizer components. The stabilizer component may be a formaldehyde donor compound.
GB 2 011 790 A1 discloses an aqueous germicidal composition comprising 0.1 to 5 parts by weight of 2-methyl-3-oxo-5-chlorothiazoline-1,2, 16 to 28.5 parts by weight of dimethylolurea and 40 to 72 parts by weight of one or more adducts which are formed from 2 mol of formaldehyde and aliphatic glycol with 2 to 8 carbon atoms and/or monoalkyl ethers of such a glycol having 1 to 6 carbon atoms in the ether group.
The Patent Abstract of Japan 02062833A (application No. 63214548) describes how a compound having amino groups can be added to a formaldehyde donor present in a water-based phase in order to prevent the release of formaldehyde.
In addition, various technical products based on N/O-formal are known. Thus, for example, the reaction product of formaldehyde or paraformaldehyde and ethanolamine (Grotan® BK═N,N′,N″-tris(hydroxyethyl)hexahydrotriazine) has been used successfully as a preservative in the cutting fluid sector. Grotan® BK is a colourless to slightly yellowish liquid with a characteristic odour. On the basis of legal provisions, it has become a requirement to label a preparation containing greater than or equal to 0.1% of hexahydrotriazine (labelling requirement from 0.1% of hexahydrotriazine as R 43). In practice, a labelling of such substances or preparations (e.g. cutting fluid emulsions) cannot be carried out. As alternatives, therefore, biocides are sought which do not lead to a corresponding labelling, but on the other hand are comparatively effective, cost-effective and are acceptable from organoleptic considerations. These biocides should not necessarily comprise a large amount of hexahydrotriazine, but at the same time can release a large amount of formaldehyde, based on the weight.
An alternative to Grotan® BK which is used is, inter alia, the 1:1 condensation product of paraformaldehyde and isopropanolamine (N,N,N″-tris(β-hydroxypropyl)hexahydrotriazine, Grotan® WS). Grotan® WS is, due to the lower content of formaldehyde, somewhat less effective than Grotan® BK, and is also more odour-intensive and significantly more expensive than Grotan® BK.
For many years, a condensation product of paraformaldehyde and isopropanolamine (weight ratio 3:2, Mar® 71 or Grotan® OX or GrotaMar® 71, N,N′-methylenebis(5-methyloxazolidine) has also been used. The commercial products are anhydrous or low-water, colourless to slightly yellowish liquids with a characteristic pungent odour reminiscent of amine and formaldehyde. The biocidal effectiveness is very good due to the comparatively high formaldehyde content. However, the odour is perceived as a disadvantage during use. In particular, the pungent odour reminiscent of formaldehyde and the formaldehyde emission have been criticized.
Although, as has been mentioned, it is known from DE 197 22 858 A1 that certain glycols have a positive influence on the odour of compositions which comprise formaldehyde donor compounds and can reduce the emission of relatively volatile substances such as formaldehyde, the addition of relatively large amounts of odour-modifying additive, however, reduces, in an undesired way, the active ingredient content, based on the total weight. At the same time, emissions of odour-modifying additive (solvent) automatically arise, these emissions are in turn undesired.
Preparations based on dimethyloldimethylhydantoin (DMDMH) or tetramethylolglycoluril are also known. Apart from the fact that DMDMH and tetramethylolglycoluril are relatively expensive, they are solids or aqueous preparations which are unsuitable for certain fields of application. For example, it is impractical if, in the preparation of a dilute cutting fluid, a solid additive has firstly to be dissolved. In addition, a water fraction often has an unfavourable effect on the (storage) stability of certain active ingredients. Aqueous preparations also often have inadequate low-temperature stability. Water automatically reduces a high formaldehyde content and has an unfavourable effect on the emission of volatile constituents.